Hundreds of Privy Counsellors have been warned they may not be able to attend the Accession Council when Prince Charles becomes king.
A letter has been sent out to all members of the body - which acts as the monarch's official advisors - to inform them attendance at the meeting, which is convened within 24 hours of the death of the sovereign and will be the first event the Prince of Wales officially attends as King when the time comes, has been significantly scaled back.
Although there are over 700 Privy Counsellors, only 200 will be able to attend following a review, with priority given to former Prime Ministers, cabinet and shadow cabinet ministers, the Archbishops of Canterbury and York, party leaders and the leaders of devolved nations, as well as senior representatives of the judiciary.
Those who fail to make the initial cut must enter an annual ballot for one of the remaining seats.
Downing Street and House of Commons leader Mark Spencer - who also serves as the Privy Council's Lord President - have authorised the change.
In a letter seen by the Daily Telegraph newspaper, Richard Tilbrook, Clerk of the Privy Council, wrote: “With the agreement of Number 10 and the Lord President of the Council, we have advised the Royal Household that - for strong safety and operational reasons - there is no option but to reduce the number of attendees to 200 if we are to deliver the first high profile event of the King’s reign to the high presentational and safety standards required of the occasion.
“The historic nature of St James’s Palace presents a number of significant challenges in terms of capacity, accessibility and crowd flow.
“The pace at which an Accession Council must take place limits significantly the additional security, infrastructure and provision we are able to make on the day.
“Taken together, these issues posed a considerable risk to the dignified delivery of an Accession Council. Even with a number of mitigations in place, there was a significant risk of overcrowding and lengthy queuing, resulting in safety issues and a compromised experience for attendees, and potentially delaying the start of the Accession Council.
“The revised attendee list will now comprise Privy Counsellors selected on an ex-officio basis, a small number of Privy Counsellors selected via an annual ballot, and certain other dignitaries.”
MP Sir Edward Leigh, who was appointed to the Privy Council three years ago, questioned why the members of the body were not consulted on the plan and warned it “risks reducing the Privy Council into a mere Disneyland showpiece, rather than a body that is central to the constitutional functioning of the United Kingdom”.
Writing a reply to Mr. Tilbrook - which has also been sent to the Prince of Wales' private secretary and Prime Minister Boris Johnson - he suggested the Accession Council be moved from St. James Palace to the more spacious Buckingham Palace of Westminster Hall.
He added: “I must also object to the proposal to have an annual ballot open to all Privy Counsellors not on the 'ex-officio' list.
“This proposal is illogical. It would mean that a Privy Counsellor who finds him or herself in Orkney, the West Indies, or Papua New Guinea on the day in question might have a place guaranteed via the ballot but be unable to use it, while a Privy Counsellor in London who is ready, willing and able to attend would, it would seem from your suggestion, be prevented from doing so.”
When Queen Elizabeth took the throne 70 years ago, she had 175 Privy Counsellors, but the number has more than tripled over the years and there are now over 700.